There have been disclosed an image reading device capable of driving a feeding device (feeding unit) for feeding a sheet of document to a reading unit, such as CIS, and a carrying device (carriage) for carrying the reading unit with a driving force of one motor. According to the related-art image reading device, a position (feeding unit-side position) in which a transmitting unit (switching gear) transmits the driving force of the motor to the feeding device and a position (carriage-side position) in which the transmitting unit transmits the driving force to the carrying device are switched, so that the feeding device and the carrying device are driven by one motor.